A team of government transport advisers has privately concluded that improving public transport will not cut road congestion, the BBC has learned.

They say the only thing that will is a road tolling system on major roads and into towns and cities.

The news comes less than a month after the Transport Department denied it was planning to make motorists pay to drive on motorways.

The team of experts has spent months analysing traffic flows and predictions.

But confidential notes from their latest meeting admit that improving public transport will not significantly reduce traffic as the government hopes.

Alarm

The notes go on to say only imposing a road toll will have any real impact and, to be effective, tolls would have to be levied on all motorways and in all urban areas.

The conclusion will alarm road users and motoring organisations.

Although this study covers only south and west Yorkshire, identical work is being carried out all over the country.

Less than two weeks ago there were reports that Lord Birt, the prime minister's own special adviser had reached the same conclusion - that road tolling to cut the jams is now inevitable.

In February, the Commission for Integrated Transport, which provides independent transport advice to the government, suggested a controversial plan to tax motorists according to the distance they drive then send them a monthly bill.

However the idea was quickly dismissed by a Transport Department spokesman who said: "There is no prospect of introducing road user charging for vehicles other than lorries in the present decade."

Motorists will be charged £5 a day to bring their cars into central London from February 2003, as part of mayor Ken Livingstone's 10-year transport plan.